An Anisotropic Damage Model for Metal Fatigue

Abstract

This paper presents the development of an anisotropic fatigue damage model to assess residual life of engineering components based on theory of Damage Mechanics (DM). This is achieved by extending the application of an anisotropic model of Damage Mechanics recently proposed by Chow and Wang (Chow and Wang, 1987a,b,c, 1988; Wang, 1987). The effect of plastic damage on fatigue damage is taken into account by establishing the required evolution equations of plastic damage. The failure criterion is based on the postulation that a macro-crack is formed when overall equivalent damage Z, which includes fatigue damage Zf and plastic damage ZP, reaches a critical value Zcr.

For the sake of illustration, the fatigue damage model is used to assess residual lives of smooth specimens under fatigue loading. The loading conditions chosen are single block loading, double block loading and overload. The predicted results show good agreement with the experimental data.